add logMessage method to locator filter (#7222)

to discourage from using Python print()

python/core/auto_generated/locator/qgslocatorfilter.sip.in

@@ -241,6 +241,19 @@ custom configuration widget.
    hasConfigWidget() must return true to indicate that the filter supports configuration.
 %End
 
+    void logMessage( const QString &message, Qgis::MessageLevel level = Qgis::Info );
+%Docstring
+Logs a ``message`` to the log panel
+
+.. warning::
+
+   in Python, do not use print() method as it might result in crashes
+   since fetching results does not happen in the main thread.
+
+.. versionadded:: 3.2
+%End
+
+
   signals:
 
     void finished();

src/core/locator/qgslocatorfilter.cpp

@@ -20,6 +20,7 @@
 #include "qgslocatorfilter.h"
 #include "qgsstringutils.h"
 #include "qgsfeedback.h"
+#include "qgsmessagelog.h"
 
 
 QgsLocatorFilter::QgsLocatorFilter( QObject *parent )
@@ -80,3 +81,8 @@ void QgsLocatorFilter::setActivePrefix( const QString &activePrefix )
   mActivePrefifx = activePrefix;
 }
 
+void QgsLocatorFilter::logMessage( const QString &message, Qgis::MessageLevel level )
+{
+  QgsMessageLog::logMessage( QString( "%1: %2" ).arg( name(), message ), QStringLiteral( "Locator bar" ), level );
+}
+

src/core/locator/qgslocatorfilter.h

@@ -271,6 +271,15 @@ class CORE_EXPORT QgsLocatorFilter : public QObject
      */
     virtual void openConfigWidget( QWidget *parent = nullptr );
 
+    /**
+     * Logs a \a message to the log panel
+     * \warning in Python, do not use print() method as it might result in crashes
+     *          since fetching results does not happen in the main thread.
+     * \since QGIS 3.2
+     */
+    void logMessage( const QString &message, Qgis::MessageLevel level = Qgis::Info );
+
+
   signals:
 
     /**